Fastener stringer stitching



May 10, 1966 J. E. BURBANK FASTENER STRINGER STITCHING Filed July 9, 1964 United States -Patent Office 3,249,976 Patented May "10, 1966 3,249,976 FASTENERSTRINGER STITCHING .Iohn E. Burbank, Middlebury, Conn., assignor to Scovll Manufacturing Company, Waterbury, Conn., a corporation of Connecticut Filed July 9, 1964, Ser. No. 381,378 1 Claim. (Cl. 24-205.1)

This invention relates to an improved construction of a zipper stringer and particularly to the attachment of a continuous filament having a row of fastener portions along one side to a tape which overlies such filament.

In sew-ing tape to coil to make a zipper Stringer, various stitches have been suggested, including several independent rows of stitching as well as the regular 402 or 403 stitch as shown and described in Fed. Std. No. 751 Stitches, Seams and Stitching.

All of these prior methods of stitching have presented problems. It is desirable to have one of the threads anchored firmly in the cord to prevent endwise sliding of the coil under stress. -In the case of a two-needle stitching, such as the above-mentioned 402 stitching, the needles automatically straddle the cord, and thus fail to penetrate it due to the natural tendency of the cord to dodge the needle. The space between thevcoil convolutions isl inadequate for the free passage of three FIG. 3 is a plan view on a larger scale of right and left stringers separated, and as they would appear from the underside of the zipper;

FIG. 4 is a cross-sectional view of the left stringer taken substantially along the line 4 4 of FIG. 3;

FIG. 5 is a cross-section showing the action of the needles in relation to the cord; and

properly sized needles an-d the use of small and weak needles causes deviation of the needles and poor stitch format-ion. In the case of smaller-sized fasteners, even the use of two needles presents difficulty because of the same crowding problem.

The present invention involves a new way to sew tape to coil and an improved product resulting therefrom. The above difficulties are overcome and there are added advantages in easy sewing, a better product While using less thread, particularly as compared to a three-needle process.

One of the resulting improvements in the product is a better coverage or shielding of the coil against heat which may be applied by a flat iron. This is due to the interlocking or looper thread crossing over the filament instead of going directly across from one needle thread to the other. In this manner, ve thread crossings of each coil filament are obtained instead of three as in the best known prior constructions.

Another advantage -is that most of the looper thread lies nearly parallel to the tape edge, thus giving a better appearance.

Pursuant to the above objectives, in my improved method, the placement of the needles is in a diagonal pattern in relation to the direction of the feed. This may be accomplished by staggering the two needles in the machine itself, or by feeding the tape and coil along a diagonal line so that the needles instead of hitting in the same space between coilconvolutions, only one needle will be in any one space, and hence the problem of crowding or congestion is avoided.

Another important advantage ofthis method is that I am able to obtain securer locking of the coil to the cord because the needle which passes through the lead space will automatically move the cord laterally and the stitch formed thereby will hold it so so that the following needle is bound to penetrate the cord.

In the accompanying drawing, I have shown for the purpose of illustration, one embodiment which the inverition may assume in practice. In the drawing: FIG. 1 is a rear view of a portion of a nished zipper made according to my invention;

stitching layout, per se;

FIG. 6 is a plan view fromthe tape side with parts broken away and further illustrating the action of the needles on the cord.

As shown in FIG. l, the finished zipper fastener involves two stringers consist-ing of flat tapes 10 and 11 with attached coil filaments 12 and 13, and a conventional slider 14. Inside the coil filaments are filler cords 15 and 15a.

The particular form of stitching used to build up a suficient overlay of protective threads for the coil elements consists of two needle threads 16 and 17 and a looper thread 18. The thread 16 will be identified as the heel thread because -it pierces through the Stringer tapes 10 or 11 adjacent the connecting loops of each coil element, and thread 17 is the head thread because it is disposed adjacent the heads of the coil elements.

A more complete description of the interrelationship of the needle threads 16 and 17 with the single looper thread 18 will be given in connection with the left str-inger of FIG. 3. The two needles Na and Nb simultaneously pierce downwardlythrough the Stringer tapes and the spaces between the coil elements, then form loops in the needle threads through which a looper finger passes for intertwining the looper threads with the needle threads, after which the needles pull up and the stringers are indexed to the next needle-stitching station.

During the stitching of the filament to the tape, only one needle at a time passes downwardly through any single individual space between coil convolutions to eliminate the congestion that results, such as when 4tWo or more needles are projected through each such space at the same time. This is accomplished by setting one needle ahead of the other in relation to the direction of feed--a distance equivalent to the spacing of the coil convolutions.

The innermost needle Na which lays the heel thread 16 will project a loop 16a while the outer needle Nb at the same time, will project aloop 17a of the head thread. When the loops 16a and 17a are projected, a looper finger (notl shown) will carry looper thread'18 through loops 17a and 16a to a considerable distance beyond the loop 16a. After the feed mechanism advances the tape and filament, the next needle stroke will simultaneously project needle thread loops 16b and 17b and looper thread 18 will be looped around both loops 16b and 17b, thus laying threads 1 and 2 over one of the coil legs L. While the loops 16b and 17b Vare projected, the looper finger will cast looper thread 18 through loops 17b and 16b a considerable distance beyond loop 16b, thus lay threads 3 and 4 over coil leg L. After the innermost needle Na operates to cast the 16 series loops, said needle will function to force the filler cord 15 outwardly toward the heads of the coil filament as shown in FIG. 6, and while in this position, the series 3 17 loops will stitch through the filler coil and hold it in place. As the cord feeds into the machine, it will first come under the influence of needle Na and the natural tendency of the cord to dodge needle-Na will necessarily result in the cord being moved into and held in position where it will be pierced by needle Nb, and thus firmly anchored by thread 17.

What I claim is: A zipper fastener Stringer comprising in combination (a) a continuous coiled lament shaped to provide a row of aligned fastener portions one for each coil convolution; (b) a tape having one edge overlapping the coil; (c) a cord extending lengthwise through said coil; (d) stitching for attaching said coil to said tape cornprising a pair of parallel needle threads forming loops arranged in the spaces between the coil convolutions, such loops being considered in pairs, each pair consisting of a loop of one `thread penetrating through saidtape, cord and coil adjacent said fastener portions of the coil, the other loop of each References Cited by the Examiner UNITED STATES PATENTS 3,135,036 6/ 1964 Burbank. 3,147,529 9/1964 Wilcken.

FOREIGN PATENTS 224,585 11/ 1962 Austria. 906,558 9/1962 Great Britain.

20 WILLIAM FELDMAN, Primary Examiner.

BERNARD A. GELAK, Examiner. 

